Thermal retarder



INVENTOR. CLARK M. OSTERHELD BY -rr'r 1 1948- c. M. OSTERHELD THERMAL RETARDER Filed Aug. 24, 1.946

n u I Patented Dec. 14, 1948 THERMAL Clark Mt Osterheli Stoughton, Wis., assignor to McGraw Electric Company, Elgin, 111., a corporation of Delaware pplication August 6 Son a-1N0. 692,

(Cl. 218-3'9)f 14 Claims. 1

water tank that shall be efiective. to cause immediate energization of an electric heater after a time-controlled switch is closed atv the start of an ofi-peak period and in case the tank is full of cold water.

Another object of my invention is to provide a water heater control system for causing energization of the electric heater of a hot water tank with a predetermined adjustable time period of delay upon closing of a time-controlled switch in case only a relatively small amount of cold Water is in the tank at that time.

Other objects of my invention will either be apparent from a description of one form of system embodying my invention or will be pointed out in the course of such description and set forth in the appended claims.

In the drawing,

The single figure is a view in vertical, longitndinal section through a domestic hot water tank having operatively associated therewith a thermal retarder embodying my invention.

I have shown a tank It having a lowerclosure member I3 which is provided with a cold water inlet pipe l5 as well as an upper closure member I] having therein a hot water outlet pipe l9. The tank I I is surrounded by a mass 2| of heatinsulating material such as mineral wool, which is held in proper operative position by an outer casing 23. I prefer to provide a single electric heater 25 which may be of a kind now in use and be clamped against the outer surface of the lower end portion of the tank and be positioned in a tunnel 21.

I provide a thermally-actuable switch mounted on the tank I 1 adjacent to the lower end thereof, this switch including a bimetal bar 29, the fixed end of which is mounted on a fixed contact member 3| while the upper end thereof is adapted to be engaged with and disengaged from a second contact 33. Birnetal bar 29 is so designed, constructed and adjusted that it will be in engagement with contact 33 when it is subject to cold water and that it will be disengaged irom contact 33 when subject to hot water.

y ld water I. mean. water the. temp ture o which. may vary between the limits oi 7D? to a a t mperature value on he order f. 1.3 whil y hot. water I ean w t th t mp at re of which is onthe order of 153 I. provi e a. sec nd e al y-ost i b s vdtoh for co trolling h e r izati n i he te 25'. hi switch comprising a bimetal bar 35. the f xed end of whi h is mounted on a contac while i s fr nd is adapted t h en aged Wi h, and e dise gag d r m a se nd fix d con act, memr. 3 Whi e the s ond or. upper therm l yfl ntrolled s ch may be. p s t oned anywh re along h k l in e m diat s n I. n sier to m it n h a -r eiv elation th tank ll at about the middle of its height.

I p ovide. ls sh ne-controlled sw tch om pr s a s ontact arm and a. second c n.- ta t a m 43. t e contact arms bein adap ed to. be he ou of en agemen with ach her during all n-peak ho durin a tw ntyourhour y and ar to eld in en g men wi h each other on all off-peak periods of a twentyfour-hour day.

For illustr ion. ay state that wh re n y one off-peak period i used, it will exten from. ab ut 10:00, M. or. 11:00 1'1.v to about 6:00 A. M.- the following morning.

A novel form of. thermal. retarder 5. comp ises a tu ember 41 which. may be made of a hieh-heat-conduotin ma ial uch as. brass, c ppe or inum and which tube. is losed at the bottom end and p n at. the top. At. the to! there is scou ed. to the op n end a bel ows 9 w i is cl sed, a i s upper end by a. met plate provide a fluid 53. such as. wat r, n the container 41, which fluid is a p ed to be vapo ized by means to be hereinafter described so that the bellows 49 will be caused to expand with results. to be hereinafter set forth.

A mall wattage heatin coil 55 is insul tedly mounted on and around the tube 41. By small Wattage I mean a i n. which e am unt, o n gy tr s nt he t is n. he rder of to 10 watts and in w ich it is possible to vary the exact amount of energy ansl ted int heat.

I provi a pa r of pply irc it ond ctors 51 and 59 o Which ondu tor 51. is connected with contact arm 4|. Contact arm 43 is connected by a c ndu tor fil to co ta t 38. Cont ct 31 s c nnected by a nducto 63 o a o ductor 55. w ch extends from on c nta t membe 6.! f a pair including a second fixed contact member 69 which are adapted to be engaged with and be disengaged from a contact bridging member ll which is insulatedly mounted on closure plate 5! of bellows 49. The other end of conductor 65 is connected with one terminal of the electric heater 25, the other terminal of which is connected by a conductor 12 to contact 33. Contact 3! is connected by a conductor 13 with the second supply circuit conductor 59. A conductor connects fixed contact member 69 and conductor 6| to one terminal of the low wattage heating coil 55, the other terminal of which is connectedto one terminal of an adjustable rheostat 11, the other movable terminal 79 being connected by a conductor 8| with contact 33 and conductor 12.

Let it now be assumed that the tank is filled with cold water and that contact arms 4| and 43 have just been moved into engagement by a continuously operative timing means so that the time is, say 10:00 P. M. Since the tank is full of cold water the bimetal arms 29 and 35 will be in engagement with their cooperating contact members 33 and 39 whereby an energizing circuit through heater 25 is closed traceable as follows: from supply circuit conductor 51, through the engaged contact arms 4| and 43, through conductor 6|, bimetal bar 35, conductors 63 and 65, heater 25, conductor 12, through bimetal bar 29 and from there through conductor 13 to the second supply circuit conductor 59.

This energization of heater 25 will therefore cause heating up of the water in the tank and particularly the water in the upper portion of the tank, the water in the uppermost portion of the tank becoming hot substantially first. When the layer of cold water uppermost in the lower part of the tank has been dropped to a position where bimetal arm 35 is in heat-receiving relation with hot water in the tank, it will move out of engagement with contact 39 whereby ole-energization of the electric heater 25 is efiected.

A second heating circuit for the heating coil 55 was closed substantially at the same time, this circuit being traceable as follows: from supply circuit conductor 51, through the engaged contact arms 4| and 43, conductors 6| and 15, through heater 55, through that part of rheostat 11 which is in circuit, through conductor 8|, through bimetal bar 29 and from there through conductor 13 to the second supply circuit conductor 59. As has already hereinbefore set forth, the amount of energy translated into heat in heating coil 55 is relatively small, the adjustment by means of the adjustable rheostat 11 being such that it will require about four hours or say until 2:00 P. M. before the contact bridging member H has been moved upwardly far enough to engage the contacts 61 and 69. If now the bimetal bar 35 is moved to open position whereby electric heater 25 is de-energized before contact bridging member H engaged contacts 61 and 69, the engagement of contact bridging member H with contacts 61 and 69 closed a second energizing circuit through heater 25 traceable as follows: from supply circuit conductor 51, through the engaged contact arms 4| and 43, through conductor 6|, through the engaged contact members 69, II and 61, through conductor 65, heater 25, conductor 12, bimetal bar 29, which is still closed and from there through conductor I3 to the second supply circuit conductor 59.

The energization of heater 25 will therefore continue until substantially all of the water in the tank is hot, that is, has been heated to a tem perature on the order of say 150 F. when bimetal bar 29 will move to open position whereby the heater coil 25 is de-ene'rgizedjand it is-assumed 4 that it will take less than four hours to heat all the rest of the water in the tank to a temperature of F. If it does not heat all of the water in the tank before the contact arms 4! and 43 are disengaged, the time-controlled switch will effect de-energization of electric heater 25 whereby all of theparts may return to their normal or inoperative position.

The specific form of thermal retarder disclosed and claimed herein is effective to cause an adjustable but predetermined time period of delay in the energization of heater 25 after closure of the time-controlled switch hereinbefore described.

Various modifications may be made in the de vice embodying my invention without departing from the spirit and scope thereof and all such modifications clearly coming within the scope of the appended claims shall be considered as part of my invention.

I claim as my invention:

1. A water heater control system for a hot water tank comprising an electric heater, said system comprising a first thermally-actuable heater circuit control switch adapted to be in heat-receiving engagement with water in the tank near the lower end thereof and to be in open position when subject to hot water and to be in closed position when subject to cold water, a second thermallyactuable heater circuit control switch adapted to be subject to the temperature of water intermediate the ends of a tank and to be in closed position when subject to cold water and to be in open position when subject to hot water, a thermal retarder heater circuit control switch unit comprising an elongated tubular member, an expansible and contractibl'e bellows secured to one end of said tubular member, fluid in said tubular member, an electric heating coil on said tubular member, a heater circuit control switch adapted to be closed when said bellows has expanded a predetermined amount and an ofi-peak time-controlled heater circuit switch adapted to be closed during off-peak hours of a twenty-four-hour day, said electric heater being energized immediately upon closure of said time-controlled switch through said first and said second thermally actuable switches andsaid time-controlled switch when said tank is full of cold water.

2. A water heater control system for a. hot water tank comprising an electric heater, said system comprising a first thermally-actuable heater circuit control switch adapted to be in heat-receiving engagement with water in the tank near the lower end thereof and to be in open position when subject to hot water and to be in closed position when subject to cold water, a second thermally actuable heater circuit control switch adapted to be subject to the temperature of water inter mediate the ends of a tank and to be in closed position when subject to cold water and to be in open position when subject to hot water, a thermal retarder heater circuit control switch unit comprising an elongated tubular member, an expansible and contractible bellows secured to one end of said tubular member, fluid in said tubular member, an electric heating coil on said tubular member, a heater circuit control switch adapted to be closed when said bellows has expanded a predetermined amount and an off-peak time-con trolled heater circuit switch adapted to be closed during off-peak hours of a twenty-four-hour day, said electric heater being energized with a predetermined time period of delay after closure of said time-controlled switch, through said first thermally-controlled switch, the switch closed by 5 -caid bellows andjthe time-controlled switch, when saidfirst thermally-controlled switch only is sublect to cold water.. 1 i 1 .3. A water heater control system as set forth in claim 2 and including means for varying said pre- 5 determined time period of delay. v i

4. A water heater control system asset forth i claim 2 and including manually-actuable means for varying .said predetermined time period of delay.

v5. A water heater .controlsystem as set. forth in claim 2 and including amanually-actuab1e rheostat connected in series with said electric heatin coil .ior varyingsaid predetermined time period of delay.

6. A water heater control system fora hot water tank comprising an electric heater, ,said; system comprising a first thermallyractuable heater circuit control switch adaptedto be in heat-receiving engagement with water in the tank near the 4 lower end thereof and to be in open position when subject to hot water and to be in closed position when subject to cold water, a second thermallyactuable heater circuit control switch adapted to be subject to the temperature. of water intermediate the ends of a tankand to be in closed position when subject to coldwater and to be ;in open position when subject to hot water, a thermal retarder heater circuit control switch unit comprising an elongated tubular member, an expansible and contractible bellows secured to one end of said tubular member, fluid in said tubular member, an electric'heating coil on said tubular member, a heater circuit control switch adapted to be closed when said bellows has expanded a predetermined amount and an oil-peak timeecontrolled heater circuit switch adapted to be closed during ofi-peak hours of a twenty-four-hour day, said electric heater being energized with'a predetermined time period of delay after closure of said time-controlled switch, through said first thermally-controlled switch, the switch closed by said bellows and the time-controlled switch, when said first thermally-controlled switch only is subject to cold water, said first thermally-actuable switch de-energizing said electric heater when the tank is substantially full of hot water.

7. A water heater control system for a hot water tank comprising an electric heater, said system comprising a first thermally-actuable heater circuit control switch adapted to be in heat-receiving engagement with water in the tank near the lower end thereof and to be in open position when subject to hot water and to be in closed position when subject to cold water, a second thermally-actuable heater circuit control switch adapted to be subject to the temperature of water intermediate the ends of a tank and to be in closed position when subject to cold water and to be in open position when subject to hot water, a thermal retarder heater circuit control switch unit comprisin an elongated tubular member, an expansible and contractible bellows secured to one end of said tubular member, fluid in said tubular member, an electric heating coil on said tubular member, a heater circuit control switch adapted to be closed when said bellows has expanded a predetermined amount and an olfpeak time-controlled heater circuit switch adapted to be closed during oil-peak hours of a twentyfour-hour day, said first and second thermallyactuable switches and said time-controlled switch being connected in series circuit with each other and with said electric heater, the switch actuated by said bellows being connected in parallel cir- "6 :cuit withtsiaid second switch, the energizadon :of said electric heating .coil being controlled iointly "by said first thermallymicable switch andisaid time-controlled said electric ihe'ater bein' adapted to be energimeddmmediately upon :closure of said tune-controlled switch, "through :said first and second :switch and said time-controlled switch 'in case said first :and second are 'bothsubjectltoacoldwater. v u

8. A water heater control system for :a hot watertank comprising an :electric heater, :said system comprising afirst thermallyeactnable heater circuit control switch adapted to be ,in heat-receiving engagement with water-in the tank near the lower end thereoi and to :be in .OPEIIPOSihlDIl when subject to hot water andv to be "in closed position when subject to cold water, azisecond thermally actuahle heater circuit .gcontrol :switch adapted to be subject to the temperature or water intermediate the ends of a tank :and'to he in closed position'when subject :to cold waternn'd .to be in open position when subject to hot water, a thermal retarder heater circuit .controlswitch unit comprising an elongated tubular member, an expansible and contractible bellows secured to one end of said tubular member, fluid in said tubular member, an electric heating coil on :said tubular member, a heater circuit control switch adapted to be closed when said bellows has-expanded a predetermined amount and an off-peak time-controlled heater :circuit switch adapted to be closed during oil-peak hoursofatwenty-f ourhour day, said first and second thermally-actu able switches and-said time-controlled switch being connected in series circuit with each other and with said electric heater, the switch actuated by said bellows being connected in parallel circuit with said secondswitch, the energization of said electric heating coil being controlled jointly by said first vthermally-actuable switch and 'said time-controlled switch, said electric heater being adapted to be energized with a predetermined time period of delay after closure of said timecontrolled switch, through said first switch, said time-controlled switch and said switch actuable by said bellows in case only the first switch is sub ject to cold water.

9. A water heater control system for a hot water tank comprising an electric heater, said system comprising a first thermally-actuab-le heater circuit control switch adapted to be in heat-receiving engagement with water in the tank near the lower end thereof and to be in open position when subject to hot water and to be in closed position when subject to cold water, a second thermally-actuable heater circuit control switch adapted to be subject to the temperature of water intermediate the ends of a tank and to be in closed position when subject to cold water and to be in open position when subject to hot water, a thermal retarder heater circuit control switch unit comprising an elongated tubular member, an expansible and contractible bellows secured to one end of said tubular member, fluid in said tubular member, an electric heating coil on said tubular member, a heater circuit control switch adapted to be closed when said bellows has expanded a predetermined amount and an oil-peak time-controlled heater circuit switch adapted to be closed during oil-peak hours of a twenty-fourhour day, said first and second thermally-actuable switches and said time-controlled switch being connected in series circuit with each other and with said electric heater, the switch actuated by said bellows being connected in parallel cirperiod of delay.

said electric heating coil being controlled jointly by said first ther'mally-actuable switch and said time-controlled switch, said electric heater bein adapted to be energized with a predetermined time period of delay after closure-of said tinie controlled switch, through said first switch, said time-controlled switch and said switch actuable by said bellows in case only the first switch is subject to cold water said first thermally-actuable switch de-energizing said electric heater when the tank is substantially full. of hot water.

10. A water heater control system as set forth in claim 8 and including means for varying said predetermined time period of delay.

11. A water heater control system as set forth in claim 8 and including manually-actuable means for varying said predetermined time period of delay.

12. A water heater control system as set forth in claim 8 and including a manually-actuable .rheostat connected in series with said electric heating coil for varyin said predetermined time 13. A water heater control system for a hot water tank comprising an electric heater, said 'system comprising a first thermally-actuable heater circuit control switch adapted to be in heat-receiving engagement with water in the tank and to be in open. position when subject to hot water and to be in closed position when subject to cold water, a thermal retarder heater circuit control switch unit comprising an elngated tubular member, an' expansible and contractible bellows secured to one end of said tubular member, fluid in said tubular member, an. electric heating coil on said tubular member, a bellows-actuated heater circuit control switch ,adaptedto be closed when said bellows has expanded a predetermined amount, circuit conductors connecting said heating coil of said re tarder in series with said first thermally-actuable control switch to be controlled thereby, and con ductors connecting said electric heater of said tank and said bellows-actuated switch in series with each other and together in parallel with said heating coil, whereby said electric heater is adapted to be energized under control of both said first thermally-actuable control switch and said bellows-actuated switch of said retarder.

14. The combination of the immediately preceding claim wherein said first thermally-actuable heater circuit control switch has its heat receiving engagement with the water near the lower part of the tank, and wherein there is included, a second thermally-actuable heater circuit control switch adapted to be subject to the temperature of water at a position in said tank above that of said first thermally-actuable switch and to be in closed position when subject to cold water and in open position when subject to hot water, said second thermally-actuable switch being connected in parallel with said bellows-actuated switch, whereby said retarder is ineffective for delaying energization of said electric heater of said tank when said second thermally-actuable switch is subject to cold water.

CLARK M. OSTERHELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,744,716 Antonelli Jan. 28, 1930 1,974,302 Finlayson Sept. 18, 1934 1,978,362 Fonseca Oct. 23, 1934 2,371,258 Osterheld Mar. 13, 1945 

